Handler for the transporting of flat substrates for application in the semi-conductor industry

ABSTRACT

The proposal is for a handler for the transporting of flat substrates, in particular or wafers ( 9 ) for application in the semi-conductor industry between at least two stations with a mobile planar carrying arm ( 6 ) for taking up a substrate as well as the means for layering information of the substrate in the area of a pre-given place on the carrying arm ( 6 ). The invention is based on the task of avoiding detrimental effect to the underside of a substrate during layer positioning and the generation of particles on layer positions. This problem has been solved by providing an oscillator ( 4 ) for the generation of a longitudinal ultrasonic vibration which works in conjunction with the carrying arm ( 6 ) in such a way that on the planar carrying arm ( 6 ) an essentially stationary vibration with at least one vibration amplitude can be adjusted which facilitates a levitation of a substrate ( 9 ) set down on it and that the means of layer information for the substrate for lateral positioning is achieved exclusively be interaction with the edge area of a substrate ( 9 ).

[0001] The invention concerns a handler for the transportation of flat substrates for application in the semi-conductor industry, in particular wafers in accordance with the generic term of claim 1

STATE OF TECHNOLOGY

[0002] In semi-conductor production it is known that each contact of a wafer with an area of support for example in a stock cassette or during transport from work stations on the carrying arm of a wafer handier can generate particles which can have detrimental effect on the production yield.

[0003] Furthermore, it has been shown that sections of a wafer, which come into contact with an area of support no longer provide sufficient surface quality to be used in a regular production process which involves photo-lithographic steps.

TASK AND BENEFITS OF THE INVENTION

[0004] The invention is based on the task of providing a handler, in particular for wafers, with which the problems described above can be avoided.

[0005] This task is solved by the features of the claim 1.

[0006] The invention first assumes a handler for the transportation of flat substrates to be used in the semi-conductor industry, in particular wafers, between at least two stations which includes a mobile sheet carrying arm for taking up a substrate in a pre-given position on the carrying arm . The core of the invention lies in the provision of a oscillator for the generation of a longitudinal ultrasonic oscillation, that the oscillator works in conjunction with the carrying arm in such a way that on the sheet carrying arm an essentially stationary vibration with at least one internode can be generated which facilitates a levitation of a substrate laid on it and that the means for stacking data of the substrate are designed for lateral positioning exclusively through an interaction with the marginal area, preferably the rim of a substrate. With this procedure, a substrate can be taken up without significant contact with the underside of a work station by means of the carrying arm, transported by a movement of the carrying arm to another work station and there put down in same way, namely without significant contact with the underside of the substrate. In this way not only can unnecessary particle generation through interaction of the carrying arm with an area of support be avoided, but also the underside of a substrate can be processed without any loss of quality for example in a photo-lithographic production step. This method of procedure is based on recognition of the fact that during combined effectiveness of a carrying arm with an oscillation generator, the carrying arm is a flexural resonator in which near field levitation is employed to lift a substrate when an essentially stationary vibration forms on the flexural resonator. The means for lateral positioning of the substrate prevent a “wandering” of the levitated substrate on the carrying arm . For this the means for lateral positioning have a completely targeted effect on the rim area of a substrate only, preferably by tactile positioning only on the outside edge of a substrate in order to avoid an undesirable interaction, particularly of inside areas, with the underside of the substrate.

[0007] From the U.S. Pat. No. 5.810.155 an object transport device is known which uses acoustic levitation. This object transport device includes a transport distance. The transport distance is set into oscillation on the one hand by an ultrasound generator, whereby in another part of the transport distance and absorber is provided. In this way a wandering bending wave by means of which an object lying on it can be transferred along the transport distance with the wave. This patent thus follows a different principle and is therefore not relevant for the present invention.

[0008] The basic principal of acoustic levitation on a bending oscillator generated into vibration by an oscillator is described in the publication “The Journal of the Acoustical Society of America”, Vol. 100, No. 4, Part 1, Oct. 1996, Hashimoto et. al. “Near-field acoustic levitation of planar specimens using flexural vibration”. From this publication however, there is no evidence to be seen for the integration of such a bending oscillator in a concrete handler for flat substrates.

[0009] Near-field levitation is particularly favorable when the oscillator works in conjunction with the carrier in such a way that on the planar carrying arm an essentially stationary vibration occurs with a number of vibration points.

[0010] Moreover, it is of particular advantage if the oscillator is attached to the carrying arm in such a way that the longitudinal vibration axis is vertical to the plane of the planar carrying arm . In this way the energy of the oscillator is transmitted particularly effectively to the carrying arm.

[0011] In an especially preferred version of the invention, the carrying arm is formed in such a way that a substrate taken up in the area of a pre-given lateral position, for example a transport position, is accessible from underneath. This can be achieved by means of sections in the carrying arm or through an appropriate form shape, for example fork or tongue form or similar. These shapes are based on the recognition that levitation of a component on a carrying arm formed in such a way functions without any problems, even if the area of support of the substrate is smaller than the substrate surface. Finally it also has the advantage that the substrate can be easily taken up and set down again.

[0012] The means for lateral positioning of a substrate can in a preferred model version of the invention include one or more suction heads, which work on the edge area of the substrate. In this way the substrate at the edge comes only into minimum contact with the suction points of the suction heads.

[0013] In a further model version of the invention, the substrate is centralized laterally into the required position by means of at least one buffer which works on the edge area of a substrate. Positioning with one or more buffers can take place in conjunction with suction heads, which by means of their suction effect, draw the substrate towards the buffers.

[0014] In another preferred model version of the invention, the means for lateral positioning include a clamping device. With a clamping device, an edge of the substrate can be held so to speak as with pincers.

[0015] Lateral positioning of a substrate in the required position can preferably also be achieved when the carrying arm is tilted from horizontal position i.e. it is in a slanted position. This model version is particularly advantageous in conjunction with appropriately arranged buffers.

[0016] In a further particularly preferred model version of the invention, devices are provided which facilitate a completely contact-free lateral positioning of a substrate. In this way the substrate as a whole can be handled completely contact-free, which means that particle generation or surface contamination resulting from contact can be completely avoided.

[0017] Contact-free positioning can be achieved by means of a reflector or several such reflectors arranged along the side of the substrate, which preferably are not in connection with the carrying zone of the carrying arm .

[0018] Moreover, at one additional oscillator can be used in the area of the substrate for contact-free lateral positioning, which is preferably not in connection with the carrying zone of the carrying arm.

[0019] For contact-free positioning one or more jets can also be used, through which gas or air streams.

[0020] Depending on the purpose of utilization, several carrying arm s can be arranged either next to one another and/or on top of one another and/or opposite one another. These carrying arm s can be provided with one or more oscillators for the generation of a bending vibration, whereby the one oscillator or several oscillators can be arranged on and/or under the carrying arm s.

DRAWINGS

[0021] Several model examples of the invention are represented in the drawings and described further with details of additional benefits and individual features. The figures show the following

[0022]FIG. 1 the front piece of a wafer handler with oscillator in a movement system in perspective view

[0023]FIGS. 2a to 5 various carrying arm geometries in perspective view from below and in part from above

[0024]FIGS. 6a to 11 Various model forms for facilitating lateral positioning of a substrate on a carrying arm in perspective view from above, and in FIG. 6b also from below

DESCRIPTION OF THE MODEL EXAMPLES

[0025]FIG. 1 shows a “front piece” 1 of a wafer handler 2 on a transfer system 3.

[0026] The front piece 1 comprises essentially an oscillator 4, which via coupling elements 5 is mechanically firmly connected to a carrying arm 6 here by way of example extending on both sides. The oscillator 4 is arranged by means of connecting elements 7on an intermediate piece 8 which is connected with the transfer system 3. This means that the carrying arm 6 is connected with the transfer system only via the coupling elements 5 and the oscillator 4.

[0027] With the carrying arm 6 the principle of a bending oscillator is implemented, which is initiated by the oscillator 4, for example of an ultrasonic source with 24 kHz. In the acoustic near-field of the carrying arm 6 having been set into bending vibrations, can for example on both sides an exemplary 200 mm Wafer 9 be held at a levitation height of approx. 0.1 to approx. 0.5 mm

[0028] Lateral positioning of the wafer 9 is solved in FIG. 1 by adjustable tactile buffers (not shown).

[0029] In FIGS. 6a to 11, further possibilities of lateral positioning are shown in diagram form.

[0030] In FIG. 6a lateral positioning is carried out by means of two suction heads 10, 11, which take effect either at the edge as illustrated in FIGS. 6a and 6 b or in the edge area from above or below on the wafer (not shown) and hold this in place by means of vacuum pressure. The arrows 12, 13 in FIG. 6a symbolize the direction of suction.

[0031] With this procedure, a wafer 15 which is set down on a carrying arm 14 remains completely accessible from the front.

[0032] An alternative to this is shown in FIG. 7 in which lateral positioning of a wafer 15 on a carrying arm 14 is achieved by a combination of suction heads 16, 17 and buffers 18, 19. The wafer 15 is drawn in the direction shown by the arrows in the figure but does not touch the suction heads 16, 17 because the buffers 18, 19 place the wafer a little distance in front of the suction heads 16,17.

[0033] In accordance with FIG. 8a and b a wafer 15 can be fixed laterally on a carrying arm 14 also by means of a clamping device 20 with exemplary two clamping jaws 21 and 22. In FIG. 8a arrows show the direction of clamping.

[0034]FIG. 9a and b shows lateral positioning by means of buffer pairs 23, 24, whereby at least the buffer pair 24 is sliding (see arrow in FIG. 9a).

[0035]FIG. 10 shows a slanting carrying arm 29, on the front end of which buffers 31 have been attached, against which a wafer 15 levitated on the carrying arm slides.

[0036] In FIG. 11 the wafer 15 is laterally positioned contact-free on the carrying arm 14 by four ultrasound generators 30. This represents a particularly elegant possibility for holding the wafer completely contact free during a transfer.

[0037] Furthermore it is possible to position a wafer laterally on a carrying arm with jets, from which air streams out. The jets can be arranged in the same way as the ultrasound generator 30 in FIG. 11 or one or two jets can be used which press the wafer against one or more buffers.

[0038] Depending on the surrounding circumstances, various forms of carrying arms can be used, corresponding to FIGS. 2a to 5 b. The illustration of FIG. 2a and b is the example of a forked carrying arm 25. In FIG. 3a and 3 b a plate form carrying arm 26 is illustrated.

[0039]FIG. 4a shows the utilization possibility of several carrying arms which form a support plane, in the example of two carrying arms 27. Finally, FIG. 5 with one carrying arm stands for carrying arms with partial sections. The forms 25, 26 and 27 described above can also have additional partial sections as required.

[0040] It came as a surprise to establish that all the forms mentioned can be set into bending vibration with an oscillator so that levitation of a wafer 15 set down on them is possible. According to the state of technology, only rectangular forms of bending vibrations are known, which in addition are always greater in surface area than the components levitated with them.

[0041] The form of the carrying arms 25 to 29 is preferably adjusted to suit the surrounding conditions so that the wafer can be taken up and set down particularly easily.

[0042] reference number designations:

[0043]1 front piece

[0044]2 wafer handler

[0045]3 transfer system

[0046]4 oscillator

[0047]5 coupling element

[0048]6 carrying arm

[0049]7 connecting element

[0050]8 connecting piece

[0051]9 wafer

[0052]10 suction head

[0053]11 suction head

[0054]12 arrow

[0055]13 arrow

[0056]14 carrying arm

[0057]15 wafer

[0058]16 suction head

[0059]17 suction head

[0060]18 buffer

[0061]19 buffer

[0062]20 clamping device

[0063]21 clamping jaw

[0064]22 clamping jaw

[0065]23 buffer pair

[0066]24 buffer pair

[0067]25 carrying arm

[0068]26 carrying arm

[0069]27 carrying arm

[0070]28 carrying arm

[0071]29 carrying arm

[0072]30 ultrasound generator

[0073]31 buffer 

1. Handler for the transporting of flat substrates for use in the semi-conductor industry, especially wafers (9, 15), between at least two stations, with a movable planar arm (6, 14, 25-29) for the taking up of a substrate and the means (10, 11, 16-24, 31) for layer information of the substrate in the area of a pre-given position on the carrying arm (6, 14, 25-29) identified by the provision of an oscillator (4) for the generation of a longitudinal ultrasonic vibration, and by the fact that the oscillator works in conjunction with the carrying arm (6, 14, 25-29) in such a way that on the planar carrying arm (6, 14, 25-29) an essentially stationary vibration with at least one vibration node is adjustable which facilitates a levitation of a substrate (9, 15) set down on it and that the means for layer information of the substrate (10, 11, 16-24, 31) are formed for lateral positioning exclusively by means of an interaction with the edge area of a substrate.
 2. Handler according to claim 1 identified in that the oscillator (4) works in conjunction with the carrying arm (6, 14, 25-29), in such a way that on the planar carrying arm an essentially stationary vibration with a number of vibration nodes can be set.
 3. Handler according to the previously described claims identified in that the oscillator (4) is arranged on the carrying arm (6, 14, 25-29) in such a way that the longitudinal vibration axis is arranged vertically to the plane of the planar carrying arm.
 4. Handler according to the previously described claims identified in that the carrying arm (6, 14, 25-29) is formed in such a way that a substrate taken up is accessible from below in the area of a pre-given position.
 5. Handler according to the previously described claims identified in that the means for lateral positioning comprise a suction head (10, 11, 16, 17).
 6. Handler according to the previously described claims identified in that the means for lateral positioning have a buffer (18, 19,23, 24, 31).
 7. Handler according to the previously described claims identified in that the means for lateral positioning comprise a clamping device (20).
 8. Handler according to the previously described claims identified in that the carrying arm (29) is set up in a slanting position.
 9. Handler according to the previously described claims identified in that devices (30) are provided for contact-free lateral positioning of the substrate (15).
 10. Handler according to the claim 9, identified in that the devices comprise a sonic reflector arranged on the side of the substrate.
 11. Handler according to the claim 9 or 10, identified in that the devices comprise at least one additional oscillator (30) in the area of the substrate, which preferably is not in connection with the carrying area of the carrying arm (14).
 12. Handler according to the previously described claims identified in that several carrying arms are arranged either on top of one another and/or next to one another and/or opposite one another and are provided for by one or more oscillators which are positioned on and/or under the carrying arms. 